So i have built a combustion cannon and a few pneumatic cannons before all have been in the style of Design A. My question, are there any advantages to using the U-shape like in design B? Which provides better performance?

Which is the best for a pneumatic cannon using a sprinkler valve? A or B?

i think i'm going inline 2' 4" pvc chamber down to 1" for the valve then back to 2" then from there have a female adapter for interchangeable barrels. if there's a place where i can make these images it would help a lot